The micro-blogging service Twitter is an effective PR instrument, but one fraught with risk for celebrities who want to juice their notoriety by connecting directly and on their own terms with the public. Forgoing the filtering function of publicists, they may endear themselves to fans even more powerfully; or they may end up with feet in mouths and eggs on faces. You can do a lot of damage in 140 characters.

In this regard, TV personality Miyoko Omomo's now famous tweet of Dec. 19 was considered reckless at first. Omomo had recently discovered that her ex-husband, journalist Toru Yamaji, had had an affair with another 40-something TV personality, Kuniko Asagi, while Omomo and Yamaji were still married. It didn't matter that the couple divorced in 2006 because, as Omomo eventually revealed, she was never completely sure why Yamaji asked for a divorce in the first place. Four years later she found out and was so angry she announced the infidelity retroactively on her Twitter account while on her way to Narita Airport to catch an overseas flight.

The response was instantaneous. TV "wide shows" (current affairs variety programs) and tabloids picked up the story the next day, and since Omomo was unavailable they turned their attention to Asagi. As it happens, she is a regular commentator on the TBS show "Hiruobi" but understandably didn't turn up for a few days. When she next appeared in public it was one of those standing press conferences that seem neither planned nor spur-of-the-moment. She tried to explain the situation while her lawyer, Junichiro Hironaka (whose clients also include political honcho Ichiro Ozawa), lingered behind her.